My kids won some small goldfish at a carnival 2 weeks ago. Two of the fish developed puffy growths under their mouths and died. I think it was cotton mouth disease. I bought Melafix but it did not help. There is one fish left and I was wondering if I shoud change the water(I just changed the water 2 days ago right before the second fish died). Should I continue to treat the water with Melafix to keep the other fish from getting sick?

You can treat with medicated food ( antibiotics ), potassium permanganate in the water, injection of antibiotic if possible. Also topical treatment of wounds.

Improve water conditions, quarantine new fish. It almost always indicates that a parasitic infection is going on and an accumulation of organic debris, including fecal matter. So please do waterchanges every day about 10% and continue treatment with Melafix AND Pimafix.

Sometimes those poor fish at markets and shows, carnivals are not in best nick, unfortunately. Sometimes the owners just want to get rid of them because they do not want to care too much, it became inconvenient or so.

I've been on a market the other day, they had a few tanks with goldies, one fellow was a pretty big boy, but it seemed to me that he had fin rot... poor thing

What kind of tank do you have?Did you test for all water parameters like Ammonia, Nitrite, Nitrate, pH?Do you have good filtration and aeration?

The goldfish (Sheldon) is in a temporary 1 gallon tank with a pump that we happened to have on hand for right now. My husband lost his job a while back so I have not been able to buy a larger tank yet, but I plan on getting a 10 gallon tank soon. The tank does not have a filter, so I have been changing tabout 20 percent of the water out everyday.I did not know alolt about goldfish until we got the carnival fish 2 weeks ago. I have been reading online about goldfish care to prepare for a larger tank. I tested the ph and it was fine. I knew nothing about cycling the water until a worker at Petsmart told me. I looked at different products such as one called Stability to cycle the water. Do these products help? Sheldon seems to be disease free so far.

Do you use a water conditioner when changing the water? It's like a chemical that neutralizes toxic substances in raw tap water. Like chlorine and chloramine.Bad water is usually the cause of most fish diseases since a fish is usually battling several bacteria and viruses at a time, but their immune system can usually handle these until some environmental problems raise the level of stress on the fish, weakening it and making it more susceptible to infection.

Get yourself a nice 20 gallon tank for the fella, if he's a common goldfish, he needs all the swimming space he can get (: And it's generally not good to keep a fish in such a small space, especially in case he might be in a bad condition from before. But just keep an eye on this dude!

Just in case, it could be good for you to buy yourself a few more text kits, for ammonia, nitrite and nitrate so that you'll be prepared for the bigger tank and the cycle! (: